This program is a study of the biochemical basis of taste, focusing on mechanisms of recognition of taste stimuli at the molecular level. This approach to investigate taste is based on measuring the direct interactions (binding) of radioactively-labeled or fluorescent taste stimuli to various types of preparation from taste tissue. For example, binding of radioactively-labeled chemostimulatory amino acids has been measured to a plasma-membrane containing fraction from the taste tissue of the catfish Ictalurus punctatus. Plasma membranes are being used to define the characteristics of the specific interactions of taste stimulus molecules with their receptor sites. BIBLIOGRAPHIC REFERENCES: Krueger, J.M., and Cagan, R.H. Biochemical Studies of Taste Sensation 4. Binding of L-(H3) Alanine to a Sedimentable Fraction from Catfish Barbel Epithelium. J. Biol. Chem. 151, 88-97 (1976). Cagan, R.H., and Kare, M.R. Chemical Senses: Influence on Variability of Nutritional Adaptation. In Progress in Human Nutrition, Vol. 2, The Biological and Cultural Sources of Variability in Human Nutrition, edited by S. Margen, Academic Press, 1976, in press.